#include <stdio.h>

int main(int argc, char *argv[]) {

    char en[4];
    scanf("%c%c%c", &en[0], &en[1], &en[2]);
    for (size_t i = 0; i < 3; i++)
    {
        for (size_t z = i+1; z < 3; z++)
        {
            if(en[i]>en[z]){
                en[3] = en[i];
                en[i] = en[z];
                en[z] = en[3];
            }
        }
    }

    printf("%c%c%c", en[0], en[1], en[2]);

    return 0;
}